No matter your level, the size of your company, the industry in which you work, or your role, you need to be able to persuade and influence people. Those that do it really well do so in a way that maintains and even builds solid relationships.
What works best? Logic? Emotion? Both?
It might depend on which cognitive or social psychologist you talk to. Let's just say that the jury is still out but might be actually leaning heavily away from pure logic.
Some studies talk about the fact that you need both logic and emotion but not at the same time. In other words, you have to choose the best one for your situation. Other studies show that emotions are clearly more persuasive than logic. One study even showed that 90% of decisions are made based on emotion but that people essentially use logic to go back and justify their decision.
Not to be outdone, some cognitive psychologists refer to studies where rational arguments did actually change people's minds even with our inherent bias towards disregarding data we don't think supports our own point of view (research shows that we actually do this).
In that research, the psychologists showed that logic worked only if people had high involvement or were motivated to deliberate on the issue. In normal language, it means that it impacted them directly.
Even with the research, most of you have been taught since you were kids to put together a rational argument based on logic and information that supports it. McKinsey Consulting calls this "logical persuading", and some studies have found that people use it over 50% of the time.
At work, this shows up as "the business case." Make a compelling one that appeals to the obvious need for something based on objective information, and you are off and running on whatever it is you are trying to persuade others to do, right?
Unfortunately, almost everyone has encountered the situation where you had the best logical argument in the world and presented it well still only to find people digging in and entrenching themselves against the logic.
So does logic just not work on us crazy irrational humans?
Despite some of the research, my own practical experience would say not to abandon logic at all but couple it with another approach to increase your odds of success.
Putting it to the test in practical day to day business reality
On a daily basis, I need to persuade someone to do something that they probably already have their mind made up that they don't want to do (or at least they don't want to do it the way I want them to). Because I run a consulting business where I have literally no role based authority inside a company to get people to do things, I've been a student of persuasion and influence for years.
The ability to do it successfully literally is my livelihood.
Beyond the logic versus emotions argument, the real key is knowing the person you are trying to persuade. I have found that there is an element of logic that everyone responds to, but you have to know them well enough to pick that logical thing that resonates while also knowing what else motivates a person (this is where the emotions usually come into play).
There are almost always other emotional things at play that get in the way of the logic and don't allow it to be heard. If you can break through that, then you can make a logical case that will be heard.
A real example
I worked with a leadership team on some work that required a completely different model for how the work got done. There were many pieces to it, but one key piece meant taking people out of the business units and moving them.
The logic was all there. The financial gain was significant. The process improvement was obvious. The positive customer impact was easy to see and even quantifiable. But one of the leaders was having nothing of it.
As she dug in further against the logic and rational case, I wanted to "sell her" even more on the business value but decided to take a time out and follow up with her afterwards.
Through some probing conversation I found out that her objection wasn't to the logic (even though at the time she couldn't really articulate it that way) but to the fact that she felt personally responsible for the people she had hired into the roles, and that their lives were going to change in a way she couldn't control. It was an emotional connection issue and a commitment issue.
Once that was on the table, we were able to figure out a way to make the change in a way that felt OK for her. The emotional issue was resolved and she could then focus on the logic, ironically which she fully supported.
So it might not be logic or emotion. It just might be emotion and logic together that really works. It has worked for me for years.